Origin and sequence of chromosome replication in Escherichia coli

Bird, Robert E.; Louarn, Jean-Michel; Martuscelli, Jaime; Caro, Lucien

doi:10.1016/0022-2836(72)90559-1

Cited by 268 publications

(112 citation statements)

References 42 publications

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“…All strains derived from LN2666, a spontaneous streptomycinresistant mutant of CB0129 (F-W1485 leu thyA deoB or C supE; Bird et al 1972), except LN3073, which is a spontaneous streptomycin-resistant mutant of PK2035 (Kuempel et al 1991 ), and LN850, which is derived differently from CB0129 (Louarn et al 1985). LN3079 and LN3061 are LN2666 derivatives made A(ch'f2600)::tet and A{dif2600)::Ap ~ by homologous recombination with plasmid pFC75.1 and pFC73, respectively (integration then excision).…”

Section: Strains and Plasmidsmentioning

confidence: 99%

Restriction of the activity of the recombination site dif to a small zone of the Escherichia coli chromosome.

Cornet¹,

Patte²,

Louarn³

1996

Genes Dev.

126

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The recombination site dif is the target on the Escherichia coli chromosome of the site-specific recombinases XerC and XerD. The dif/XerC-D system plays a role during the cell cycle, probably by favoring sister chromosome monomerization or separation. A phenomenon of regional control over dif activity, also analyzed in this issue, is demonstrated here by translocation of dif to a series of loci close to the normal locus. We found that the site is physiologically active only within a narrow zone around its natural position.Competence for dif activity does not depend on the sequence of the normal dif activity zone (DAZ), because ~(diD deletions larger than the DAZ result in Dif + bacteria when dif is reinserted at the junction point. Although dif maps where replication normally terminates, termination of replication is not the elicitor. A strain with a large inversion that places dif and its surrounding region close to oriC remains Dif*, even when a Tus-mutation allows replication to terminate far away from it. Preliminary data suggest the possibility that specialized sequences separate the competent zone from the rest of the chromosome. We suspect that these sequences are members of a set of sequences involved in a polarized process of postreplicative reconstruction of the nucleoid structure. We propose that this reconstruction forces catenation links between sister chromosomes to accumulate within the DAZ, where they eventually favor recombination at d/f.[Key Words." Site-specific recombination; dif site domain of activity; E. coli chromosome organization] Received January 10, 1996; revised version accepted March 20, 1996.The

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Section: Strains and Plasmidsmentioning

confidence: 99%

Restriction of the activity of the recombination site dif to a small zone of the Escherichia coli chromosome.

Cornet¹,

Patte²,

Louarn³

1996

Genes Dev.

126

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“…In the processes involved in the termination of replication of the circular chromosome of Escherichia coli, it has been determined that the replication terminus is opposite the replication origin and is located somewhere between the trp and his loci, but the position of the replication terminus has not yet been reported with any greater precision (1)(2)(3)(4). It is also not certain if the replication terminus is a definite locus on the chromosome or if it is simply wherever the two replication forks involved in bidirectional replication happen to meet.…”

mentioning

confidence: 99%

Terminus region of the chromosome in Escherichia coli inhibits replication forks.

Kuempel¹,

Duerr²,

Seeley³

1977

Proc. Natl. Acad. Sci. U.S.A.

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In the processes involved in the termination of replication of the circular chromosome of Escherichia coli, it has been determined that the replication terminus is opposite the replication origin and is located somewhere between the trp and his loci, but the position of the replication terminus has not yet been reported with any greater precision (1-4). It is also not certain if the replication terminus is a definite locus on the chromosome or if it is simply wherever the two replication forks involved in bidirectional replication happen to meet. Various investigators have reported results that suggest that replication occurs in a unidirectional fashion in certain situations (5-7). This suggests that there might not be a locus between the trp and his loci that blocks replication forks. Termination has now been studied with several different chromosomes that replicate bidirectionally, and the results demonstrate that bacteriophage X (8) and simian virus 40 (9) do not possess a specific region of the chromosome that blocks replication forks. The plasmid R6K, however, does have a terminus that blocks replication forks (10). The Bacillus subtilis chromosome might also have a specific terminus (11-13).In order to facilitate the study of termination in E. coli, we have sought conditions in which the normal symmetrical pattern of replication of the chromosome was altered so that one replication fork would reach the terminus region earlier than the other. We have recently determined that induction of prophage P2sig5 causes bacterial chromosome replication from the site of insertion of the prophage, and one of the strains we have studied has the prophage integrated near the terminus region. The results of studies of this strain are reported here. MATERIALS AND METHODSBacterial Strains and Media. PK241 is an F-thr leu his arg thi thyA drm dnaA malA+ E. coli strain derived from CRT4624. This latter strain and bacteriophage P2tsD4csigj (which will be called P2sig5 in this paper) were obtained from Y. Hirota (14). PK289 is an F-ilv arg met thi his thyA drm E. coli strain. PM 14 is a met trp his thr thy nic ilv Proteus mirabilis strain. The PM14 F' merogenote strains containing the F'129, F'116, F'111, F'101, and F'152 episomes were obtained by mating PM14 with E. coli strains containing these episomes and selecting for His+, Thy+, Ilv+, Thr+, and Gal+ cells, respectively. The E. coli F' strains were obtained from B. Bachman.The sources of the A specialized transducing phage were as follows: Xgt-E. coli EcoRI lop-li lig+ 1 (Alig), from R. Davis (15); XflaN+ 36 (Xfla), from M. Simon; A reverse (Arev), from M. Gellert (16); XptrpED 1 (Xtrp), from C. Yanofsky (17); XCIam34bio256 (Xbio), from M. Furth. XaroD was obtained by using the procedure of Schrenk and Weisberg (18).Cells were usually grown in M9 medium (19). During incubation in the absence of required amino acids, arginine or methionine was not removed from the medium. When PK241-P2-1 cells were labeled with 32P, they were grown in low-phosphate medium (20) containing 0.2...

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“…The passive replication (5) of this prophage by the chromosomal machinery occurs in a known direction (6), the polarity of integration is known (7,8) and the DNA strands can be easily separated (9). These properties have allowed us to study, by DNA -DNA hybridization, the size distribution and the molecular polarity of the DNA made during exposure to short pulses of tritiated thymidine.…”

mentioning

confidence: 99%

Size Distribution and Molecular Polarity of Newly Replicated DNA in Escherichia coli

Louarn

Bird

1974

Proc. Natl. Acad. Sci. U.S.A.

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Newly synthesized DNA, in E. coli lysogenic for the phage X, was labeled by short pulses of [ In bacteria, at least some of the newly synthesized DNA appears as short chains (Okazaki fragments) that are subsequently joined to long molecules (1-3). Whether such discontinuous replication occurs on both strands or only on one is an open question. Evidence, recently reviewed by Klein and Bonhoeffer (4), has been introduced for both possibilities. In order to resolve this question, in the case of Escherichia coli replication, we have studied the molecular polarity of newly synthesized DNA at a given point on the E. coli chromosome, the prophage lambda. The passive replication (5) of this prophage by the chromosomal machinery occurs in a known direction (6), the polarity of integration is known (7,8) and the DNA strands can be easily separated (9). These properties have allowed us to study, by DNA -DNA hybridization, the size distribution and the molecular polarity of the DNA made during exposure to short pulses of tritiated thymidine.EXPERIMENTAL DESIGN Fig. 1 shows two possible models for the manner in which the new DNA strands are formed (1). In model A, (continuous-discontinuous replication) synthesis occurs continuously in the 5' -> 3' direction by addition of nucleotides, to long DNA chains, at the 3' end. Replication in the 3' --5' direction occurs by synthesis of short chains (5' --3', i.e., backward relative to the movement of the replication fork) that are subsequently joined to long DNA.Abbreviation: SSC, standard saline-citrate solution (0.15 M sodium chloride-0.015 M sodium citrate, pH 7); 6 X SSC means that the concentration of the solution used is 6 times that of the standard saline-citrate solution. In model B (discontinuous replication) both strands are synthesized first as short chains then are joined to long DNA.We have isolated the radioactive short fragments made during a short pulse of radioactive thymidine in a strain lysogenic for X, and hybridized these fragments with the separated strands of the phage DNA. Model B predicts that radioactive fragments will hybridize to both strands of phage X, whereas model A predicts that fragments will hybridize only to strand I of X and long DNA will hybridize to strand r.We have found that replication occurs according to model A in our polA + strain. In a polA -strain two size classes of fragments are formed: the smaller class, 10 S, corresponds to the fragments found in the polA + strains; the other class, 12-50 S, corresponds to the strand that is elongated continuously in polA + strains. MATERIALS AND METHODSBacterial and Bacteriophage Strains. The E. coli Ki2 strain CB 0129 (F-Thy-Leu-BI-) was used. Its replication pat-

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Origin and sequence of chromosome replication in Escherichia coli

Cited by 268 publications

References 42 publications

Restriction of the activity of the recombination site dif to a small zone of the Escherichia coli chromosome.

Restriction of the activity of the recombination site dif to a small zone of the Escherichia coli chromosome.

Terminus region of the chromosome in Escherichia coli inhibits replication forks.

Size Distribution and Molecular Polarity of Newly Replicated DNA in Escherichia coli

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